Quotetestcase
I believe that can be done via a GoogleVoice number. NO second SIM or cost for a second line either.

It’s via data, so no SIM involved. It’s basically VOIP for cellphones. There are several versions of multi numbers on the same phone.... the trick is getting video to work on the extra number(s). I don’t know if space’s idea of adding an extra number to your AppleID will work, but it’s worth a try. We have T-Mo’s version, which is called “Digits”,and so far I’ve only gotten video to work on Android via proprietary phone based protocol. No joy on the iPhones yet. Plus, all we’ve used so far, is numbers from the other cellphones for the extra numbers.

IOW, can get video using iPhone’s number via phone protocol on Android to another Android phone that has same protocol, but no FaceTime on iPhone using Android’s phone number; only voice in that configuration so far. “FaceTime” isn’t an option even for another iPhone’s number.... only “video”, but I haven’t figured out how to get it to drill down to a FaceTime option from there yet via the extra phone number. Of course you can still to FaceTime using other AppleID options, so maybe your email shows up as the caller, rather than the extra number. More trials need to be run.
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